This passage demonstrates the principle of the church in the church. That is, there are only a few (remnant) who are grateful enough to show it. Some people call this the pareto principle - 20% or less do 80% or more of all ministry.
Where are the other nine?
LUK 17:11 Now on his way to Jerusalem, Jesus traveled along the border between Samaria and Galilee.
LUK 17:12 As he was going into a village, ten men who had leprosy met him. They stood at a distance
LUK 17:13 and called out in a loud voice, "Jesus, Master, have pity on